According to the May 2012 issue of Game Informer, Forerunners may be alive inside the shell of the Dyson Sphere, which was erected to protect the planet from the Halo superweapon. There is no sky inside the sphere, only columns that support an artificial ceiling.

There is a new enemy force on Requiem. Of these aliens, it is said "If anything, they're kind of elevated in terms of their intelligence and complexity relative to the Covenant."[1]